3 Answers
3

Definition of shelf lifenoun
the length of time for which an item remains usable, fit for consumption, or saleable:the shelf life of fresh pastafigurativethe new strategy will be lucky if it has a shelf life of more than a few months

cookies have expiry, no TTL.TCP transport (packets) and DNS do have TTL. Although as the world has descended into madness and anarchy, some people do write very loosely about cookie TTL. Wikipedia article on TTL en.wikipedia.org/wiki/Time_to_live
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ChrisOct 5 '12 at 0:37

Wiki citation from Chris can go into the answer.
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KrisOct 5 '12 at 7:00